1. Field of the Invention
The present invention relates generally to inhalation therapy devices, and more particularly to an inhalation device which provides an incentive spirometer coupled with a metered dose inhaler (MDI) for delivering an aerosolized medication to the respiratory system.
2. Description of Related Art
The publications and other reference materials referred to herein to describe the background of the invention and to provide additional detail regarding its practice are hereby incorporated by reference.
Individuals afflicted with diseases which compromise lung function such as asthma, bronchitis, emphysema, and the like are most commonly treated by oral or aerosolized inhaled bronchodilators. Bronchodilators, anti-inflammatory agents, decongestants and other such medicines are commonly prescribed using MDI-type devices. It has been shown that MDI is a superior method of aerosol administration because the small and uniformed size of the aerosolized medication particles more effectively penetrates to the smaller branches of the bronchi.
Recent studies, have shown, however, that about 10% to 20% of patients taking MDI treatment fail to receive optimal aerosol deposition because improper or poor inhalation technique. Poor inhalation technique is generally due to inadequate inspirations, faulty timing, as well as misunderstood directions. For example, patients have difficulty using conventional MDI devices because they fail to precisely time the activation of the MDI with inhalation. Sometimes patients will inhale too quickly or neglect to hold their breath for a brief period of time in order to insure that the aerosolized medication will be sufficiently deposited into the airways.
The desired time interval of breath holding time is approximately 10 seconds, as discussed in "An Evaluation of Incentive Spirometry For Bronchodilator Therapy" (Frost, G., RRT., Vol. 24, Issue 5, p.11, 1988). It has also been proposed that a brief exhalation, followed by a slow, sustained inhalation will yield the most favorable results in terms of improved bronchodilation. Incentive spirometers, like the DHD Coach.TM. Model 22-4000 (DHD Medical Products Company) with a feedback device, are particularly useful because they train patients to inhale slowly, maximally, and hold the full breath. Such breath control enhances the patient's ability to receive optimal delivery of medication to the bronchial airways.
Examples of devices using, in combination, a small volume nebulizer and an inhalation aid, such as a spirometer, for monitoring and measuring a patient's inspiration volume and airflow rate are shown in U.S. Pat. Nos. 4,114,608, 4,259,951, 4,809,706 and 4,984,158. The devices disclosed in the aforesaid patents teach patients how to exercise and/or monitor his or her lungs while used in cooperation with a medication that can be inspired. However, none of these devices alleviate the difficulty of precisely timing manual activation of the MDI with inspiration because they do not allow the aerosilized medication to be held in suspension prior to delivery. Furthermore, these devices have the disadvantage of permitting large, untherapeutic droplets, rather than smaller, thereapeutic particles of medication to be delivered to the airways.
Accordingly, there is a need for a device which provides a simple and inexpensive way to deliver an aerosolized medication, where optimal aerosol particle deposition and particle size is achieved, and which coaches the patient to achieve slow-flow inspiration and adequate breath holding, and which alleviates the need for precise timing of manual activation of an MDI with inhalation.
Without proper delivery and deposition of aerosolized medication particles throughout the bronchial airways, the patient most likely will derive little or no benefit from this form of therapy.